[GRLUG] WMNTUG Windows 7 Meeting

[Jeff DeFouw]

On Wed, Sep 16, 2009 at 08:01:39PM -0400, Bob Kline wrote:
> http://en.wikipedia.org/wiki/Signal_%28computing%29
> 
> I seem to remember that years ago one
> of the signals was to be used so the UPS
> could signal the system that it couldn't
> hold the power up much longer.  Think ice
> storm, power plug pulled, etc.  The system
> would then put the system to bed gracefully.
> If nothing else, there are two user defined
> signal.
> 
> Seems one wouldn't need a very big UPS
> in that case, and I'd think even a big
> capacitor and arrangement could do the
> job if properly designed.  i.e., turn those
> voltage delays in to a virtue.
> 
> I don't use one - do most el-cheapo UPS's
> come with such signal outputs, and what
> would a typical PC do with them?  If anything.
> I know it was a premium feature years ago.

That's what the UPS's you see in retail stores are for -- to shut down 
the system gracefully.  Most of them use USB for communication now.  
Check the box for I/O ports and software.  If it has a serial port or 
USB, there are a few different UPS monitors in Linux you can check for 
support (apcupsd, nut).  I've never seen the POSIX signals get used.  
When the battery gets low in Linux, the normal shutdown process runs.  I 
always buy a UPS with plenty of runtime, so if there's a long power 
failure, I have plenty of time to finish what I'm doing.  I put every 
computer I own on a UPS.

-- 
Jeff DeFouw <jeffd at i2k.com>